1. Field of the Invention
The present invention relates to a pump, and more particularly to a pump that effectively avoids an impeller being damaged by back-flow current while facilitating maintenance and adjustment.
2. Description of Related Art
Pumps are widely used in people's daily life for liquid transmission. A conventional pump comprises a body and a pressurizing barrel.
The body is plastic and has a chamber defined therein and an impeller mounted rotatably inside the chamber. The impeller connects to a motor or a turbine and is driven to rotate thereby. Furthermore, the body has an inlet tube and an outlet tube that are mounted securely on the body and communicate with the chamber.
The pressurizing barrel is connected with the body via a connecting pipe and has a circuit board. A pneumatic pressurizing assembly is mounted inside the pressurizing barrel to provide additional pressure to selectively raise pressure of the pump for increased load to prevent motor burn out or damage caused by overloading when pressure in the outlet pipe is changed. The circuit board controls operation of the pressurizing barrel.
To avoid liquid in the chamber flowing back into the inlet tube when the impeller stops operation, the pump has a one-way valve mounted in the inlet tube of the body. However, the conventional pump as described does not prevent liquid remaining in the outlet tube from returning to the impeller, and this back-flow current may damage the impeller when the impeller stops.
Otherwise, the circuit board is embedded in the pressurizing barrel and causes inconvenience for maintenance, and the pneumatic pressurizing assembly is awkward to adjust.
The present invention therefore provides a pump to obviate or mitigate the aforementioned problems.